\begin{tikzpicture}[>=Stealth]
    \draw (-0.8, 0.6) rectangle (0.8, 1.4);
    \node at (0, 1) {$x = ?$};
    \draw [->] (0, 0.6) -- (0, 0.2);
    \node at (0, 0) {$4 + x = 7$};
\end{tikzpicture}
